1. Field of the Invention
The present invention relates to a power supply device, and more particularly, to a battery system balancing control method for performing balancing control with aid of reference voltage information, and to an associated battery system.
2. Description of the Prior Art
In recent years, the environmental issues are widely discussed. In order to prevent the natural environment from becoming worse, it is encouraged to use more rechargeable batteries in many places. For example, electric vehicles (EVs) or hybrid electric vehicles (HEVs) are typical in many nations. Additionally, it seems unlikely that the conventional battery system having a single battery is suitable for implementing machines that are driven by high voltages, such as the EVs mentioned above, since it is typically needed to have a total voltage of tens or hundreds of volts for driving the EVs. As a result, connecting multiple batteries in series to form a serial connection battery system is required.
The problems encountered in the serial connection battery system are much different from that of a single battery. In the serial connection battery system, the electrical characteristics of respective batteries are not consistent. When the number of batteries that are connected in series within the serial connection battery system is increased, the influence due to the differences between the batteries may become greater, where the electricity imbalance between the respective batteries in the serial connection battery system may easily occur. For example, some of the batteries in the serial connection battery system may be overcharged. In another example, some of the batteries in the serial connection battery system may be over-discharged. As a result, the overall performance of the serial connection battery system may degrade, and the life of the serial connection battery system may be shortened. Therefore, electricity imbalance has become an issue.
In accordance with the related art, the balancing control circuit within the conventional serial connection battery system requires a special design, and some problems described in the following typically exist. For example, when it is required to change the number of batteries in the conventional serial connection battery system (e.g. the output voltage specifications of the conventional serial connection battery system need to be changed), the balancing control circuit needs to be modified accordingly. In addition, in a situation where the design of the balancing control circuit is updated in response to user requirements, mechanical elements within the conventional serial connection battery system (e.g. some case components) need to be modified accordingly. The situations described above may result in an increase of related costs, and typically, there is no the usage flexibility when implementing according to the related art.